1. Field
The technology of the present application relates generally to antenna structures and, and more specifically to a hybrid antenna structure combining laser direct structuring material and a two shot molding process.
2. Background
Wireless devices use a variety of different types of antennas. The styles can be classified in two generic categories: external and internal. External antennas are generally more efficient than internal antennas. But internal antennas are less prone to damage and usually more aesthetically pleasing. The technology of the present application generally relates to metalized plastics and has specific utility with electronic components such as internal antennas.
Internal antennas can be made using a number of different methodologies. One method of making internal antennas is a stamped metal or embossing technique. The stamped metal technique uses thin metal that is stamped and formed into the size and shape needed to form the needed radiator design. This piece of metal is then connected to a non-conductive carriage to form the antenna assembly. Another technique used to manufacture antennas is the flexible film approach. This technique uses a thin layer of conductive material such as copper attached to a non-conductive substrate such as Capton or Mylar. The substrate has a thin layer of adhesive on the back surface. To form the radiator geometry, the copper that is not needed is removed by using conventional printed circuit board manufacturing methods. This flexible film is then attached to a rigid structure such as the antenna carriage or the handset housing wall.
One popular method of manufacturing an antenna involves a multi-shot injection molded, selectively plated technique. The multi-shot technique typically provides an injection molded base of non platable plastic with a platable plastic injection molded onto selective portions of the base. The antenna base is formed by a first injection mold process of a base layer or carrier. The base layer typically is a plastic, composite, or synthetic material that has positive strength, durability, and ductility characteristics. However, the base layer also is a non-platable plastic. In other words, conductive traces necessary to form the radiator cannot be adhered or plated to the non-platable plastic. Thus, the base layer is placed into a second injection mold and a platable substrate is molded to the base layer. The platable substrate is typically a plastic, composite, or synthetic material to which conductive traces (most typically copper) can be adhered or plated to form the radiator. Once the base layer and platable substrate layer are formed by the two shot molding process, the structure is plated using, for example, an electroplating technique to plate conductive material to the platable plastic. The conductive material plates substantially all the exposed surface area of the platable plastic to form the radiating structure for the antenna. Generally, the non-platable base and the platable substrate are selected to provide a good mechanical and chemical bond to inhibit the plating process from interfering with the bond between the non-platable and platable parts.
Multi-shot molding, selectively plating methods to form antennas has numerous advantages. For example, the manufacturing of the final design is relatively repeatable and low cost. Other advantages are generally known in the art. However, the process also has numerous disadvantages. For example, the tooling for the process is expensive and the molds frequently need to be changed as the antenna design changes (particularly to accommodate variations in the radiator).
Recently, another popular method of manufacturing an antenna involves using a laser direct structuring process. The laser direct structuring process provides an injection molded base of a material that can be selectively activated by a laser (a.k.a laser drawing on the material). The selectively activated portions of the base are platable. Thus, the laser would be used to selectively activate the material with the radiation pattern desired. The material is plated such that conductive traces plate to the activated portions. One type of material usable for this process is generally known as VECTRA® liquid Crystal polymer from Ticona Engineering Polymers, a business of Celanese, but other materials as a generally know in the art are possible. Generally, a laser direct structuring material includes a plastic that includes a laser sensitive metal complex that may be activated when exposed to the laser light. The metal complex is such that it does not drastically affect the polymer's dielectric properties.
The laser direct structuring method of forming antenna structures also provides numerous advantages. For example, the production is repeatable and flexible. The portion of the material to be activated for the radiator can be varied by reprogramming the laser structure. The laser direct structuring method also has some disadvantages. For example, laser direct structuring material is relatively expensive and has less advantageous material properties.
Thus, against this background, it would be desirous to develop an improved antenna structure.